Geodynamics of continents and convergent plate margins

地质特征，如山脉，火山和经济矿藏，是地球表面以下发生的过程的结果，直接取决于成分，温度和应力。一些过程在几分钟内发生（例如，地震）而另一些则需要数百万年（例如，山建筑）。 我的研究计划涉及在很长一段时间内发生的过程，重点是北美和南美西部。这两个地区的特点是巨大的山脉带，这些山脉带是由海洋构造板块下降到大陆下方形成的，这一过程称为俯冲。然而，大陆变形和造山运动的细节仍然知之甚少。在某些地方，由于海洋板块在大陆下方近水平移动（称为平板俯冲），可能导致变形增强。除了区域变形外，山区带还受到地壳和刚性地幔内局部重力驱动变形的影响。对于北美洲和南美洲，变形发生在海岸500-1000公里范围内。东部界限对应于旧大陆的地区，据信太冷和太强而无法变形。 我的项目旨在了解俯冲和造山的动力学。在接下来的五年里，我的小组将研究三个主要课题： a）评估平板俯冲及其对大陆变形的影响 B）分析山区内的局部尺度动力学，包括重力减薄和软弱地壳的侧向流动 （三）考察山脉东界。为什么邻近的大陆没有变形，边界的几何形状是否为山脉带的形成提供了线索？ 这项工作将与8名研究生和至少5名本科生一起进行。我们将使用计算机模型来研究数百万年来的变形动力学。这些模型为地表地质记录提供定量预测（例如，地形的变化）和地球物理测量（例如，地震速度的空间变化）。与北美西部和南美现有观测结果的比较使我们能够确定模型行为是否合理。相反，这些模型加强了对观测结果的解释，并指出了需要新数据的领域。 这项研究提供了深入了解造山运动和地下过程是如何记录在地表地质。我们的工作将集中在北美和南美西部，但我们的目标是确定与全球俯冲带相关的基本过程。我们的模型还提供有关地球温度和应力条件的信息。因此，这项工作与理解短期变形的条件有关（即，地震和地震危险评估），以及地热能评估、碳氢化合物潜力和矿物/钻石勘探。

Geological features, such as mountains, volcanoes and economic mineral deposits, are the result of processes occurring below the Earth's surface and depend directly on the composition, temperature, and stress. Some processes occur within minutes (e.g., earthquakes) while others take millions of years (e.g., mountain-building). My research program addresses processes that occur over long timescales, focusing on western North and South America. Both areas are characterized by large mountain belts that formed as oceanic tectonic plates descended below the continent, a process called subduction. However, the details of continental deformation and mountain-building remain poorly understood. In some places, enhanced deformation may have resulted as the oceanic plate travelled subhorizontally below the continent (termed flat-slab subduction). In addition to regional deformation, the mountain belt is affected by local gravitationally-driven deformation within the crust and rigid mantle. For North and South America, deformation occurs within 500-1000 km of the coast. The eastern limit corresponds to areas of older continent, believed to be too cold and strong to deform. My program aims to understand the dynamics of subduction and mountain-building. Over the next five years, my group will study three main topics: a) an assessment of flat-slab subduction and its effect on continent deformation b) an analysis of local-scale dynamics within mountain belts, including gravitational thinning and lateral flow of weak crust c) an examination of the east boundary of the mountain belt. Why does the adjacent continent not deform, and does the geometry of the boundary provide clues to mountain belt formation? This work will be carried out with 8 graduate students and at least 5 undergraduates. We will use computer models to study the dynamics of deformation over millions of years. The models provide quantitative predictions for the surface geological record (e.g., changes in topography) and geophysical measurements (e.g., spatial variations in seismic velocity). Comparisons with existing observations in western North and South America allow us to determine whether the model behaviours are reasonable. Conversely, the models enhance the interpretation of observations and point to areas where new data is needed. This research provides insight into mountain-building and how subsurface processes are recorded in surface geology. Our work will focus on western North and South America, but we aim to identify fundamental processes relevant to subduction zones globally. Our models also provide information about the temperature and stress conditions in the Earth. Thus, this work is relevant to understanding the conditions for short-term deformation (i.e., earthquakes and seismic hazard assessment), as well as geothermal energy evaluation, hydrocarbon potential and mineral/diamond exploration.